ext2, dax: set ext2_dax_aops for dax files

Sync syscall to DAX file needs to flush processor cache, but it
currently does not flush to existing DAX files.  This is because
'ext2_da_aops' is set to address_space_operations of existing DAX
files, instead of 'ext2_dax_aops', since S_DAX flag is set after
ext2_set_aops() in the open path.

Similar to ext4, change ext2_iget() to initialize i_flags before
ext2_set_aops().

Fixes: fb094c90 ("ext2, dax: introduce ext2_dax_aops")
Signed-off-by: NToshi Kani <toshi.kani@hpe.com>
Suggested-by: NJan Kara <jack@suse.cz>
Cc: Jan Kara <jack@suse.cz>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: "Theodore Ts'o" <tytso@mit.edu>
Cc: Andreas Dilger <adilger.kernel@dilger.ca>
Cc: <stable@vger.kernel.org>
Signed-off-by: NJan Kara <jack@suse.cz>

fs/ext2/inode.c

@@ -1448,6 +1448,7 @@ struct inode *ext2_iget (struct super_block *sb, unsigned long ino)
 	}
 	inode->i_blocks = le32_to_cpu(raw_inode->i_blocks);
 	ei->i_flags = le32_to_cpu(raw_inode->i_flags);
+	ext2_set_inode_flags(inode);
 	ei->i_faddr = le32_to_cpu(raw_inode->i_faddr);
 	ei->i_frag_no = raw_inode->i_frag;
 	ei->i_frag_size = raw_inode->i_fsize;
@@ -1517,7 +1518,6 @@ struct inode *ext2_iget (struct super_block *sb, unsigned long ino)
 			   new_decode_dev(le32_to_cpu(raw_inode->i_block[1])));
 	}
 	brelse (bh);
-	ext2_set_inode_flags(inode);
 	unlock_new_inode(inode);
 	return inode;